Generally, the processing of a light-sensitive material is carried out by subjecting the light-sensitive material, after it is exposed, to steps of development, desilvering, water-washing, and drying. The color-developing solution (P1), bleach-fixing solution (P2), and rinsing solution (PS), for use in the steps, are replenished, respectively, by certain amounts, after processing of a light-sensitive material has continued for certain amounts of processing.
In recent years, from the standpoint of environmental loads, regarding the processing of light-sensitive material, there is strong demand for reducing the amount of the waste solution, by reducing the replenishment, and/or by regenerating the waste solution. As a means for reducing the waste solution, an apparatus for concentration by distillation at reduced pressure is already in practical use, and this contributes to reducing the number of repetitions in recovering the waste solution, and the space for storing the waste solution. However, because of widespread use of mini-labs, further-increased efficiency is desired, and reuse of the waste solution becomes an important aim.
An example of reducing the waste solution amount by the manner used conventionally by distillation at reduced pressure, is the method in which the processing waste solution is solidified and powdered, so that the resultant powder is reused as a solid processing agent, as disclosed in JP-A-10-288829 (“JP-A” means unexamined published Japanese patent application). The fixing waste solution contains silver ions, and therefore the silver ion concentration is increased to the extent that desilvering of the light-sensitive material is prevented, if the waste solution is put straight to solidification and powderization, to reuse the resultant powder as a solid processing agent. For this reason, in this mode, the silver ions are removed by electrolysis, etc., before water is removed from the fixing waste solution, and thereafter the waste solution is solidified. The solidified matter is 100% reused, to be regenerated as a solid processing agent, by replenishing the component that is decreased by the development processing.
This system, however, cannot be a preferred mode, because equipment to remove the silver ions is necessary, and space to accommodate the equipment is required, thereby resulting a high cost. In addition, this system cannot solidify a small amount of the waste solution without causing loss.
Further, according to this method, the bleaching effect is reduced by the formation of Ag2S and the formation of Fe(II) by reduction of the bleaching agent: Fe(III) itself, when the silver ions are electrolytically reduced. As a result of continued rapid running processing while regenerating and reusing the solid processing agent according to this mode, such new problems as fading of cyan color, filter clogging, and staining of the light-sensitive material have occurred.
Still further, the distillation at reduced pressure, serving as the means to reduce the waste solution amount, is not desirable, because it requires a vacuum pump to reduce the pressure, and there is associated concern that applying excessive heat to the waste solution may generate decomposition gases, because the bleach-fixing solution contains ammonium salts and sulfites.